ALSA: pcm: fix the fix of the runtime->boundary calculation

Commit 7910b4a1db63fefc3d291853d33c34c5b6352e8e in 2.6.34 changed the
runtime->boundary calculation to make this value a multiple of both the
buffer_size and the period_size, because the latter is assumed by the
runtime->hw_ptr_interrupt calculation.

However, due to the lack of a ioctl that could read the software
parameters before they are set, the kernel requires that alsa-lib
calculates the boundary value, too.  The changed algorithm leads to
a different boundary value used by alsa-lib, which makes, e.g., mplayer
fail to play a 44.1 kHz file because the silence_size parameter is now
invalid; bug report:
<https://bugtrack.alsa-project.org/alsa-bug/view.php?id=5015>.

This patch reverts the change to the boundary calculation, and instead
fixes the hw_ptr_interrupt calculation to be period-aligned regardless
of the boundary value.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 7 insertions, 2 deletions

diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index a2ff86189d2a..22aff180dd1f 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -439,8 +439,13 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream,
                 snd_pcm_playback_silence(substream, new_hw_ptr);
 
         if (in_interrupt) {
-                runtime->hw_ptr_interrupt = new_hw_ptr -
-                                (new_hw_ptr % runtime->period_size);
+                delta = new_hw_ptr - runtime->hw_ptr_interrupt;
+                if (delta < 0)
+                        delta += runtime->boundary;
+                delta -= (snd_pcm_uframes_t)delta % runtime->period_size;
+                runtime->hw_ptr_interrupt += delta;
+                if (runtime->hw_ptr_interrupt >= runtime->boundary)
+                        runtime->hw_ptr_interrupt -= runtime->boundary;
         }
         runtime->hw_ptr_base = hw_base;
         runtime->status->hw_ptr = new_hw_ptr;